What if non-specialist teachers taught all mandatory courses?

My high school history teacher passed away recently. I think he was a good teacher, so while trying to think of something to write in his obit's guestbook I was trying to think of why I think he's a good teacher. And what I came up with is he got the material into my head. History was neither my favourite nor my least favourite subject. I don't have any particular passion for it, and I only took the required course. But this teacher easily and painlessly got me to a mindset where, even 15 years later, the material that is relevant to whatever I'm doing or thinking about is there in my head. When we were talking about a coalition government last year, I could name-check King-Byng and modify a well-known historical quote to come up with coalition if necessary but not necessarily coalition. I knew enough about the Upper Canada Revolution that I groked and could banter with @RebelMayor. I know what the Boer War was and how Canada got caught up in it. I know why we have Catholic schools, and I know why so many of my co-workers are ex-Catholic. I can name-check all the major characters and plot points from both world wars. I know what a Bennett buggy is and what the On-to-Ottawa Trek was. I don't know everything about everything, but I have a solid grounding and know where I need to do more research. While this teacher must have had a passion for history, it didn't permeate his work - which was a good thing! In his classroom, we could simply learn the material without being expected to pour our whole heart and soul into it, and it stuck.

In comparison, my Grade 12 English teacher had a passion for literature, and that made me detest the subject matter. He loved comparing and analyzing and dissecting, and I simply don't care that much any more once the story is over. Even the few glimmers of interest that arose naturally were promptly extinguished, smothered by his constant demand. I found a Shakespearian sonnet that spoke to me, and got marked down in my analysis of it for not drawing religious parallels. I memorized and understood Hamlet's "To be or not to be" soliloquy, and lost marks for not being able to write it out with the exact same punctuation. I thought Newspeak was kind of cool and was in a headspace where I could have made a rudimentary attempt at drawing parallels with the language choices of current politicians, but we had to have a fricking debate about it in front of the whole class! Overall, we studied about half a dozen major works from generally-accepted Western literary cannon (plus poetry and ISU), learned the whole hubris-hamartia-downfall thing, and I found a few things that piqued my interest. That should have been enough for a required course, but this teacher put me right off with assignments that simply didn't work out unless you had the level of passion for the subject matter that he had and I didn't.

I've had this happen in other subject areas too. Teachers who are passionate about subjects I'm indifferent about smother any sparks of interest I might have developed, whereas teachers who are more blasé make subjects I wouldn't normally care about seem more approachable without hindering any existing interest.

So, to address this, what if all required courses in school were taught by non-specialist teachers? They didn't study the subjects in university, they don't have any particular passion for them, but they learned them in high school just like everyone else and now have to refamiliarize themselves in order to teach them. So they understand what it's like to struggle with the subject matter or to have to figure it out despite a lack of enthusiasm, and can get the basics into everyone's brains. Students who then find the subject particularly interesting can go on to study it in elective courses taught by specialist teachers who also have a passion for the subject matter, while students who don't particularly care can absorb the basics without having the subject ruined by a teacher's enthusiasm for fussy and finicky aspects of the subject matter.